The functional traits of tropical tree species are known to be important indicators of ecological characteristics and performance. However, their implications for the processes that maintain species diversity, such as negative density dependence and habitat preferences, remain poorly understood.
Here, we undertake such an analysis using generalized linear mixed models of seedling survival that account for overall neighborhood densities, functional similarity-weighted neighborhood densities and habitat variables in a 20-ha tropical forest dynamics plot in Xishuangbanna, southwest China. We use this analysis to uncover the relative importance of conspecific density dependence, functional density dependence and habitat factors on seedling survival, and therefore to generate new insights into the ecological implications of functional traits in tropical forests.
Results/Conclusions
Seedling survival was found to be maximized in neighborhoods containing functionally similar species, despite the occurrence of conspecific negative density dependence. The edaphic and topographic properties of sampling plots significantly interacted with these processes, indicating that density dependence and habitat preferences were acting simultaneously.
We conclude that the competitive superiority of functionally similar species in their preferred habitat is a major determinant of seedling survival, driving the dynamics of this tropical tree community in combination with conspecific negative density dependence and habitat filtering, and potentially providing an explanation for high levels of species diversity in tropical forests